From: Thomas Gleixner <tglx@linutronix.de>
To: "Reshetova, Elena" <elena.reshetova@intel.com>
Cc: "mingo@redhat.com" <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"tj@kernel.org" <tj@kernel.org>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>,
"lizefan@huawei.com" <lizefan@huawei.com>,
"acme@kernel.org" <acme@kernel.org>,
"alexander.shishkin@linux.intel.com"
<alexander.shishkin@linux.intel.com>,
"eparis@redhat.com" <eparis@redhat.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"arnd@arndb.de" <arnd@arndb.de>,
"luto@kernel.org" <luto@kernel.org>,
"keescook@chromium.org" <keescook@chromium.org>,
"dvhart@infradead.org" <dvhart@infradead.org>,
"ebiederm@xmission.com" <ebiederm@xmission.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"axboe@kernel.dk" <axboe@kernel.dk>
Subject: RE: [PATCH 01/15] sched: convert sighand_struct.count to refcount_t
Date: Mon, 23 Oct 2017 12:26:47 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.20.1710231223450.4241@nanos> (raw)
In-Reply-To: <2236FBA76BA1254E88B949DDB74E612B802B4359@IRSMSX102.ger.corp.intel.com>
On Mon, 23 Oct 2017, Reshetova, Elena wrote:
> > On Fri, 20 Oct 2017, Elena Reshetova wrote:
> > How did you make sure that these atomic operations have no other
> > serialization effect and can be replaced with refcount?
>
> What serialization effects? Are you taking about smth else than memory
> ordering?
Well, the memory ordering constraints can be part of serialization
mechanisms. Unfortunately they are not well documented ....
> For memory ordering my current hope is that we can just make refcount_t
> to use same strict atomic primitives and then it would not make any
> difference. I think this would be the simplest way for everyone since I
> think even some maintainers are having issues understanding all the
> implications of "relaxed" ordering.
Well, that would make indeed the conversion simpler because then it is just
a drop in replacement. Albeit there might be some places which benefit of
the relaxed ordering as on some architectures strict ordering is expensive.
Thanks,
tglx
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next prev parent reply other threads:[~2017-10-23 10:27 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-20 12:15 [PATCH 00/15] v5 kernel core pieces refcount conversions Elena Reshetova
2017-10-20 12:15 ` [PATCH 01/15] sched: convert sighand_struct.count to refcount_t Elena Reshetova
2017-10-20 12:43 ` Thomas Gleixner
2017-10-23 10:22 ` Reshetova, Elena
2017-10-23 10:26 ` Thomas Gleixner [this message]
2017-10-23 10:45 ` Reshetova, Elena
2017-10-20 12:15 ` [PATCH 02/15] sched: convert signal_struct.sigcnt " Elena Reshetova
2017-10-20 12:15 ` [PATCH 03/15] sched: convert user_struct.__count " Elena Reshetova
2017-10-20 12:15 ` [PATCH 04/15] sched: convert numa_group.refcount " Elena Reshetova
2017-10-20 12:15 ` [PATCH 05/15] sched/task_struct: convert task_struct.usage " Elena Reshetova
2017-10-20 12:15 ` [PATCH 06/15] sched/task_struct: convert task_struct.stack_refcount " Elena Reshetova
2017-10-20 12:15 ` [PATCH 07/15] perf: convert perf_event_context.refcount " Elena Reshetova
2017-10-20 12:15 ` [PATCH 08/15] perf/ring_buffer: convert ring_buffer.refcount " Elena Reshetova
2017-10-20 12:15 ` [PATCH 09/15] perf/ring_buffer: convert ring_buffer.aux_refcount " Elena Reshetova
2017-10-20 12:15 ` [PATCH 10/15] uprobes: convert uprobe.ref " Elena Reshetova
2017-10-20 12:15 ` [PATCH 11/15] nsproxy: convert nsproxy.count " Elena Reshetova
2017-10-20 12:15 ` [PATCH 12/15] groups: convert group_info.usage " Elena Reshetova
2017-10-20 12:15 ` [PATCH 13/15] creds: convert cred.usage " Elena Reshetova
2017-10-20 12:15 ` [PATCH 14/15] kcov: convert kcov.refcount " Elena Reshetova
2017-10-20 12:15 ` [PATCH 15/15] bdi: convert bdi_writeback_congested.refcnt from atomic_t " Elena Reshetova
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